Quinolone antibiotics are known to have desirable broad-spectrum antimicrobial properties. For example, quinolone compounds for use in the treatment of ophthalmic, otic, and nasal conditions are disclosed in U.S. Pat. No. 6,716,830, the entire contents of which are incorporated by reference herein.
For use in pharmaceutical therapeutics, quinolone antibiotics must be formulated as stable, efficacious compositions. Unstable compositions can precipitate particulate matter when stored for a period of time, or can experience degradation of the active pharmaceutical ingredient or an excipient. Such compositions are unlikely to be approved by regulatory agencies due to safety concerns and other considerations.
Finafloxacin is a broad-spectrum fluoroquinolone that has been previously disclosed in U.S. patent application Ser. No. 12/829,973 for the treatment of ophthalmic, otic, and nasal infection. Finafloxacin antimicrobial activity peaks at pH ranges between 5 and 6. However, aqueous solutions of finafloxacin with this pH were found to have precipitates form in stability studies. Accordingly, new compositions of finafloxacin with better stability characteristics are needed.